Where advertising meets connector technology

Whether for commercial, industrial, or consumer markets, advertising plays an undeniable role in the marketing and sales cycle. The case for Return On Investment (ROI) is compelling as long as ads reach the target markets. With digital advertising mainstream by now, system “uptime” gets lost by integrators and installers who heavily prioritize price when selecting digital signage players, Point Of Sale/Point Of Interaction (POS/POI) terminals, kiosks, and video wall systems. Poor reliability can impact ad revenue directly.

Much of the growth in these segments is for outdoor use – along freeways, at gas station pumps, and so on. Wide temperature operation becomes a factor, such as not overheating during Phoenix summers and successfully booting and re-booting during Chicago winters. Other than the LCD itself, which is certainly challenged when it comes to temperature extremes, the “media player” computer board is challenged in several ways. Besides the obvious limitations of consumer-grade motherboards in outdoor settings, more ruggedized embedded boards can still fall short of reliability requirements when designed with consumer market connectors.

Losing your memory

Low-cost motherboards feature vertical DIMM slots or horizontal SODIMM sockets that hold system RAM. The modules and sockets were developed for computers that sit on desks and in data centers, not for outdoor environments where temperatures vary over wide ranges. Rapid temperature changes create conditions known as “thermal shock.” If the connector pins don’t wipe the gold-plated card-edge fingers well enough, tiny air pockets can form between the metal surfaces, causing code and data bit errors due to intermittent contacts or open circuits. The risk is worse depending on humidity and dust in the environment, and even shocks caused by nearby trucks rolling over potholes.

By contrast, board-to-board mated connectors are designed for high-reliability and harsh environments. They have substantial connector wiping during insertion and strong retention forces. Several memory module manufacturers used this approach and collaborated with embedded Single Board Computer (SBC) manufacturers to define a truly rugged-by-design module standard called XR-DIMM. This standard was created within the Small Form Factor Special Interest Group (SFF-SIG), a trade group that targets rugged and reliable embedded applications rather than consumer and enterprise markets.

Closing the remaining loopholes

In the non-backplane embedded computing SFF space, there are two product types: SBCs and Computers-On-Module (COMs). If the required feature set can be satisfied with an off-the-shelf SBC and I/O cards (if needed), this approach minimizes time-to-market and up-front design effort. If not, a COM and a carrier board is the new popular approach to just-right I/O.

Since both approaches (SBC and COM) are popular now, the SFF-SIG has several standards that also use board-to-board connectors for ultra-reliability. The Stackable Unified Module Interconnect Technology (SUMIT) is an expansion bus connector for mezzanine I/O cards (in other words, cards that mount horizontally, parallel to the SBC) that are secured with four mounting holes, screws, and standoffs. SUMIT consists of a mix of high-speed and easy connectivity buses in a single, compact 52-pin Samtec QFS/QMS mated connector pair. The center “blade” provides a reliable ground to the mezzanine module, even under shock and vibration loads.

Similarly, the CoreExpress specification uses Tyco board-to-board connectors for all signals that pass from processor module to custom carrier board. CoreExpress, adopted and maintained by the SFF-SIG, even goes a step further as a purely digital module. The Ethernet PHY goes on the carrier board so that analog signals do not go through the additional set of connectors, unlike other COM standards. For both SBCs and COMs, the SFF-SIG has closed the shock/vibration high-reliability connectivity loophole.

The SFF-SIG has provided a full family of specifications that can be used for computer/player boards and memory modules alike. Discriminating outdoor signage integrators and installers will need to maximize uptime and advertising revenue while greatly reducing field service “truck rolls.” In outdoor display market segments, reputations are at stake as advertisers can quickly pull ads if the coveted Frequency x Reach = Impressions equation plunges due to equipment downtime. More information about the CoreExpress, SUMIT, and XR-DIMM specifications can be found at www.sff-sig.org.